Cases of tuberculosis across the world appear to be "levelling off", the World Health Organization says.

However, the WHO warns the emergence of drug-resistant TB strains means cases could rise in the future.

Figures from the Health Protection Agency for England, Wales and Northern Ireland showed there was a slight increase in TB cases last year.

TB kills around 1.6 million people each year. The data was released to mark World TB Day on Saturday.

Drug resistance

The WHO figures show the overall number of TB cases has continued to increase - but only in line with the global population growth, reaching 8.79m in 2005, compared with 8.71 million a year earlier.

The overwhelming majority - 7.4 million - were found in Asia and sub Saharan Africa.

Mario Raviglione, head of the WHO's Stop TB programme said numbers of TB cases are going up, but only in line with population growth.

But he said the growth of new strains was worrying.

"Multi-drug resistant TB, which is resistant to the first-line drugs, is at alarming levels in the former Soviet Union and in parts of China.

"Still worse is the appearance of extensively drug resistant TB, which is a form of TB also resistant to second-line drugs.

"Essentially, we are left with very few options to treat the patients. EDR-TB has been documented so far in 35 countries worldwide, including some G8 countries.

In England, Wales and Northern Ireland, the provisional data from the Health Protection Agency showed a rise of 2% between 2005 and 2006 to 8,171 cases.

London continues to account for the highest proportion of cases - 42% - but there has been a slight decrease in the actual number of cases in the capital.

'Preventable and treatable'

Dr John Watson, head of the respiratory diseases department at the HPA, said: "Since the late 1980s the number of people diagnosed with TB has risen every year and, in line with this trend, 2006 shows a slight increase.

The key to reducing levels of TB is early diagnosis and appropriate treatment of the infection

Professor Peter Borriello, Health Protection Agency

"During 2005 we saw a large rise in the number of cases reported.

"We therefore need to be cautious about predicting future trends based on 2006 figures alone."

He added: "At this stage, it is too early to tell whether these provisional results for 2006 signify a slowing in the overall trend of increase in the number of cases."

But a British Thoracic Society survey of UK TB consultants found nine out of 10 thought cases would increase over the next decade.

Professor John Macfarlane, BTS chairman said: "This Victorian disease is on the march.

"Doctors up and down the country are warning us TB is in danger of staging a serious comeback."

Professor Peter Borriello, director of the HPA Centre for Infections, said: "The fact that we are still seeing more new cases diagnosed each year means we need to continue heightened efforts with those most affected by TB."

He added: "We need to emphasize to everyone that TB is a preventable and treatable condition.

"The key to reducing levels of TB is early diagnosis and appropriate treatment of the infection. This is where we must put our effort. Work on improving TB vaccines is also critical."